Many integrated circuits such as systems on a chip (SoC), processors, cell phone chips, and other circuits vary in performance over temperature, vary due to semiconductor process variations, and vary according to where on a wafer the chip was located during processing. Techniques are needed to compensate for these variations and to allow for operating these circuits with power efficiency while guaranteeing the expected performance. While not limited to Internet of Things (IOT), the small form factor, ultra-low power consumption, and low cost requirements make power consumption and high efficiency power management critically important in IoT applications since they directly impact the battery lifetime of the system.